1. Field of the Invention
The invention relates to apparatus for detecting fluid-borne contaminants and more particularly relates to portable apparatus which is particularly useful for detecting and/or quantification of contaminants.
2. Brief Description of the Prior Art
It has been stated that instrumentation to detect and measure airborne contaminants is the keystone of an industrial hygiene program; Occupational Hazards, pg. 54 (May, 1974). The reference goes on to stress the importance of small, portable detection devices which could be worn or carried by individual workers subject to the possibility of injury from air-borne contaminants.
Prior hereto, such portable detection devices have been of two general types. The first type comprises a sampling chamber which may contain indicator means and a pump to draw air or other gas to be monitored into the sampling chamber; see for example Occupational Hazards, supra.; Fundamentals of Industrial Hygiene (National Safety Council) pps. 361-366; and U.S. Pat. Nos. 2,489,654; 3,635,092; and 3,768,978. The second type is not generally a direct reading instrument, but comprises a vacuum chamber enclosed by a cannister. The device is merely a collection container and the collected material must be removed for subsequent analysis; see for example U.S. Pat. Nos. 3,618,393 and 3,817,108.
Neither of the previously available types of detector device have been completely satisfactory for all purposes. For example the vacuum chamber device cannot be used to give an instantaneous, direct reading. The pump operated, direct reading instruments on the other hand require skilled manipulation in the field. Very often the accuracy of a testing depends upon the volume of air of gas subjected to testing and/or the rate of air or gas passing in contact with the indicator reagent. These variables are difficult to control without an elaborate and complex pump structure. When the pump is a simple pressure bulb operated by squeezing, it is almost impossible to have reproducible results in samplings.
The apparatus of the invention provides a means of sampling gases and detecting contaminants therein in a highly accurate, reproducible and efficient manner. The volumes and flow rates of the sampled gases are highly controlled. The apparatus of the invention is also useful for detecting contaminants in liquid materials. Examples of contaminants which may be detected with the apparatus of the invention are oxygen, chlorine, methane, ammonia, etc. in air, alcohols, acids, toxins, etc. in liquids and the like.